1. Field of the Invention
The present invention relates to the fields of computer graphics and image processing, and more particularly to a method for processing a photographic texture sample image to allow borderless mapping of the texture onto any size surface.
2. Background of the Invention
Many prior art computer "paint" programs and 3-D design programs exist that allow the creation of computer graphics images. In these programs an input device, typically a "mouse", is used to draw lines, dots, patterns, and geometrical shapes on a computer screen. Depending on the sophistication of the specific paint program being used, the elements drawn on the computer screen can be created in black and white or in color and can be combined to create almost any kind of drawing or picture. More sophisticated programs allow the creation of three-dimensional objects that can be rotated and viewed from any angle on the screen. Pictures of landscapes, animals, people, and other inanimate or animate objects can be produced. Many programs offer the ability to automatically "fill", or paint, any object shown on the screen. In addition to offering different fill colors, different fill patterns may also be offered. Common fill patterns represent brick walls or latticed surfaces. The fill patterns may be simple two-dimensional designs or may feature a simulated depth component that creates shadows that give a three-dimensional effect. Fill patterns are generally stored in the form of geometrically symmetrical unit "tiles" of the patterns. To fill surfaces larger than the size of a unit tile, several identical tiles are pasted adjacent to one another to form a larger multi-tile pattern. This multi-tile pattern can then be pasted on a two-dimensional object or wrapped around a three-dimensional object to give the object the desired appearance. In order for this multi-tiled pattern to create a uniform, photorealistic effect, however, the pattern on each tile must blend seamlessly (i.e., without borders) with the pattern on each adjacent tile. Because of this requirement, only artificially computer generated symmetrical patterns such as reproductions of lattices and brick walls have been available as borderless fill patterns in prior art paint programs.
The textures of surfaces of real life objects do not have the regular geometric patterns required by prior art paint programs to allow borderless mapping of a texture pattern. Typical examples are wood, stone, cement and even water surfaces. Because these real life surface textures do not have surfaces that can be easily divided into regular, replicatable units, it has not heretofore been possible to use images of actual real life textured surfaces as borderless fill patterns in computer graphics paint programs.
Computer "paint" programs and computer aided design programs are often used by architects, engineers and others to render computer generated images of new structures or changes to existing structures. In one commercial application of these computer imaging systems, a paint manufacturer uses a computer to generate an image of a customer's house from a photograph to show the customer how the house would look with different colors of paint. In this application, an outline of the house is generated on a computer display screen by scanning an appropriate photograph. The computer operator designates the enclosed surfaces that are to be painted, and the color desired. The computer then "fills" the indicated enclosed surfaces with a red/green/blue ("RGB") pixel pattern that results, visually, in the desired color. The fill colors are usually instantly changeable such that a large number of different colors can be considered. Although these programs can relatively accurately reproduce paint colors, they, like the less specialized paint programs described above, cannot produce realistic looking textures. As a result, without the ability to generate realistic texture fill patterns, the degree of photorealism that can be achieved with prior art architectural design and rendering programs has been limited.